Wood Anatomy of Akaniaceae and Bretschneideraceae: A Case of Near-Identity and Its Systematic Implications

Wood anatomy is described in detail for the single-species families Akaniaceae and Bretschneideraceae, placed close together in most phylogenetic systems. Both families have simple perfora- tion plates with occasional scalariform plates, alternate lateral wall pitting, helical sculpturing on vessel walls, septate fibers with pits simple or nearly so, scanty vasicentric axial parenchyma, and wide tall multiseriate rays composed mostly of procumbent cells. Differences between the genera are relatively few and minor compared with resemblances; close relationship is indicated. Wood anatomy of the two families resembles that of Sabiaceae and, to a lesser extent, that of other Sapindales. The wood is distinctive within Capparales whether that order is defined traditionally or in the light of molecular studies. Wood data are compatible with an interpretation that Akaniaceae and Bretschneideraceae diverged from near the base of Sapindales.